SAN FRANCISCO — The top prosecutors in San Francisco and New York, seeking ways to curb thefts of mobile devices, said Monday they will reserve judgment of Apple's new security feature designed to make it harder to reactivate a stolen iPhone.

San Francisco District Attorney George Gascon and New York Attorney General Eric Schneiderman have been asking the leading wireless device makers to create a "kill switch" that would render stolen phones useless. The prosecutors said they aren't judging Apple's new activation lock feature until they can fully determine its effectiveness.